RESUMEN
Two-coordinate coinage metal complexes have been exploited for various applications. Herein, a new donor-metal-acceptor (D-M-A) complex PZI-Au-TOT, using bulky pyrazine-fused N-heterocyclic carbene (PZI) and trioxytriphenylamine (TOT) ligands, was synthesized. PZI-Au-TOT displays decent thermally activated delayed fluorescence (TADF) with a quantum yield of 93% in doped film. The crystals of PZI-Au-TOT show simultaneous TADF, polymorphism, and linearly polarized luminescence (LPL). The polymorph-dependent emission properties with widely varied peaks from 560 to 655 nm are attributed to different packing modes in terms of isolated monomers, discrete π-π stacked dimers or dimer PLUS. Two well-defined microcrystals of PZI-Au-TOT exhibit linearly polarized thermally activated delayed fluorescence with a degree of polarization up to 0.64. This work demonstrates that the molecular rotational flexibility of D-M-A type complexes endows an integration of multiple functions into one complex through manipulation of supramolecular aggregation. This type of complexes is expected to serve as a versatile platform for the fabrication of crystal materialsfor advanced photonic applications.
RESUMEN
Colloidal assembly has emerged as an effective avenue for achieving polarized light emission. Here, we showcase the efficacy and versatility of the magnetic colloidal assembly in enabling both linearly and circularly polarized luminescence. Colloidal europium-doped NaYF4 nanorods with surface-bound Fe3O4 nanoparticles are magnetically assembled into linear or chiral superstructures using corresponding fields created in permanent magnets. In a uniform magnetic field generated by opposing poles, the assemblies exhibit photoluminescence with intensity tunable in response to the magnetic field direction, which is higher when the nanorods are perpendicular to light propagation than when they are parallel. The obtained superstructures display strong linearly polarized luminescence when the nanorods are aligned vertically, exhibiting a high degree of polarization up to 0.61. In a quadrupole chiral field generated by permanent magnets, the assemblies emit left-handed or right-handed polarized light depending on the position of the sample placement, attaining a g-factor of 0.04. Furthermore, the superstructures immobilized in a hydrogel film are found to retain their chirality, exhibiting opposite chiroptical responses depending on the sample orientation. The magnetic colloidal assembly approach facilitates the convenient and efficient generation of polarized light emissions from nonmagnetic luminescent materials, thus creating opportunities for tailoring light behavior in developing innovative optoelectronic devices.
RESUMEN
Room-temperature phosphorescent (RTP) liquid crystal materials have garnered considerable attention because of their significant applications in organic light emitting diodes, polarized light emitting materials, and so forth. How to efficiently synthesize pure organic RTP liquid crystals and regulate their performance is of great significance. In this article, we propose a simple and feasible method to synthesize RTP liquid crystals and manipulate their properties through copolymerization. We constructed RTP liquid crystal copolymers by copolymerizing a phosphorescent monomer bearing biphenyl mesogen with a phosphorescent monomer bearing a dibenzofuran chromophore. All the synthesized copolymers show a liquid crystal property because of the introduction of biphenyl mesogen. Meanwhile, by changing the composition of copolymers, it is possible to regulate their RTP performance, including luminescence color and lifetime. As the content of the PMDFM0C component in copolymers increases, the phosphorescence lifetime gradually increases. For poly(MDFM0C(0.46)-co-MBi18C(0.54)), the phosphorescence lifetime can reach 463.0 ms. Moreover, the phosphorescence color of the PMDFM0C component in copolymers changes with the copolymer composition, which can induce variable room-temperature phosphorescence. In addition, when oriented, liquid crystal copolymer films can emit linearly polarized fluorescence and linearly polarized phosphorescence. The linearly polarized phosphorescence dichroic ratio and polarization ratio values of the oriented poly(MDFM0C(0.46)-co-MBi18C(0.54)) film are 3.33 and 0.50, respectively.
RESUMEN
Sub-1â nm nanowires (SNWs) combine the properties of inorganic materials and polymers. They can be highly oriented through assembly, and can also be easily processed. Meanwhile, aggregation-induced emission luminogens (AIEgens) show high potential for optical applications, but they are usually hard to process. The combination of SNWs and AIEgens can enrich both of their applications. In this study, we report that the fluorescence emission intensity of the AIEgens-SNW dispersion is dramatically enhanced due to the flexibility of SNWs. Furthermore, we fabricate two kinds of functional films with circularly polarized luminescence (CPL) and linearly polarized luminescence (LPL) activities. The construction of CPL materials didn't require any chiral chemicals. The construction of LPL materials didn't require an additional stretching process. As a result, we endowed common achiral AIEgens with a high dissymmetry factor of 0.033 and a polarization ratio of 0.44, respectively.
RESUMEN
Nano- and micromaterials with anisotropic photoluminescence and photon transport have widespread application prospects in quantum optics, optoelectronics, and displays. But the nature of the polarization information of the out-coupled light, with respect to that of the source luminescence, has never been explored in active optical-waveguiding organic crystals. Herein, three different modes (selective, anisotropic, and consistent) of polarized-photon out-coupling are proposed and successfully implemented in a set of 2D organic microcrystals with highly linearly-polarized luminescence. It is found that the polarization direction and degree of the luminescence out-coupled through different waveguiding channels can either be essentially retained or distinctly changed with respect to those of the original luminescence, depending on the molecular arrangement and the orientation of transition dipole moments of the crystal. This work demonstrates the promising potential of 2D emissive microcrystals in multi-channel polarized photon transport.
RESUMEN
Traditional luminescent liquid crystals (LLCs) suffer from fluorescence quenching caused by aggregation, which greatly limits their further application. In this work, a kind of novel LLCs (named carbonized polymer dot liquid crystals (CPD-LCs)) are designed and successfully synthesized through grafting the rod-shaped liquid crystal (LC) molecules of 4'-cyano-4-(4â³-bromohexyloxy) biphenyl on the surface of CPDs. The peripheral LC molecules not only increase the distance between different CPDs to prevent them from aggregating and reduce intermolecular energy resonance transfer but also make this LLC have an ordered arrangement. Thus, the obtained CPD-LCs show good LC property and excellent high luminous efficiency with an absolute photoluminescence quantum yield of 14.52% in the aggregated state. Furthermore, this kind of CPD-LC is used to fabricate linearly polarized devices. The resultant linearly polarized dichroic ratio (N) and polarization ratio (ρ) are 2.59 and 0.44, respectively. Clearly, this type of CPD-LC shows promising applications for optical devices.